A potential flow computer model that can handle blade row interaction problems has been used to analyze the circumferential static pressure distribution at the trailing edge plane of the last rotor in an axial compressor which is produced by a downstream stator/strut system. The computer model is based on the Douglas-Neumann formulation. The code was used to design a circumferentially nonuniform stagger angle distribution for the stator that reduced the static pressure disturbance on the rotor. The predicted circumferential static pressure distribution and its resulting frequency content at the rotor trailing edge station for the baseline (uniform circumferential stagger angles) stator and for the optimized stator are compared to static pressure data and derived frequency content from engine tests of each configuration. The results show good agreement between the model predictions and the test data. The results are further confirmed by measurements of rotor strain levels with the baseline stator and with the optimized stator, which show a proportional decrease in rotor strain for the optimized stator configuration. Since incorporation of this low-cost modification, there has been no evidence of vibratory induced rotor distress, thereby improving engine reliability and maintainability and enhancing customer satisfaction.

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